Circuit Emulation over IP (CEoIP) is a technology that provides a circuit like relationship to systems that are coupled together via the Internet. Because the coupled systems do not share a common clock source, it is necessary to derive an adaptive clock. Limitations on the accuracy of clocks derived using adaptive clock algorithms determine the type of communication that is possible between systems that employ such.
There are inherent limitations to the accuracy of a clock derived using adaptive clock algorithms. One such limitation is clock wander. Clock wander is an inherent consequence of adaptive clock derivation. While a limited amount of clock wander is fine for many applications, certain applications such as mobile wireless applications require a more accurate clock.
Standard algorithms for generating an adaptive clock rely on packet arrival versus departure characteristics as a means to derive the clock. For example, technologies such as the Bora Bora Network Module uses an algorithm that compares the average dejitter buffer levels identified within a given period to derive the clock.
In order to meet conventional wander specifications a clock accuracy of 15 parts per billion or better is required. One serious drawback of conventional methodologies is that network behavior can cause occasional errors in the calculations. It should be appreciated that network effects can be excluded from the calculations to a certain extent by using a large number of samples. However, the number of samples cannot be increased beyond a certain limit as such increases would increase the time taken for computation and which in turn would increase the wander.